PROJECT SUMMARY SARS-COV-2 and the associated respiratory disease, COVID-19, has been linked to over 100,000 deaths globally since fall of 2019. Severe COVI9 and associated mortality has strongly been correlated with several comorbidities including age, diabetes, immunodeficiencies and cardiovascular diseases. How behavioral or lifestyle factors, in particular tobacco use, influence the course of COVID19 has not been directly examined. Tobacco use, smoking and vaping, is a particular concern since it is directly linked to poor lung health and increased susceptibility to bacterial and viral pulmonary infections including SARS and MERS coronaviruses. Furthermore, patients that use tobacco products are at higher risk for the comorbidities such as, diabetes and cardiovascular diseases that are risk factors for COVID19. SARS- COV2 infection and tobacco use both trigger and perpetuate a dysfunctional inflammatory cytokine response in the lung. We hypothesize that smoking and vaping are primary risk factors associated with severe COVID19 and that they directly contribute to morbidity and mortality by exacerbating the uncontrolled pulmonary cytokine storm. We will adapt transcriptomics approaches established for our current R61, ?Effect of Opioid Use Disorder on HIV Latent Reservoirs and Immune Dysfunction Assessed by Single-Cell Transcriptomics? to gain insights into COVID19 mechanism of disease. We will initially obtain blood samples from the Boston Medical Center COVID19 biorepository collected from COV19+ smokers and nonsmokers and compare to COV19-negative individuals and perform state of the art digital drop single cell RNA sequencing, single cell ATAC-sequencing and computational analysis to provide insights into key innate immune signatures that directly contribute to COVID19. Although we will initially focus on blood since this is an easily obtainable tissue and often provides an immunological footprint of disease, we will compare blood with other clinical tissue samples including lung fluids as they become available. The completion of these studies will provide new insights into COVID19 biomarkers and dysregulation of specific inflammatory pathways. A primary goal is to use the results from these proposed experiments to generate new hypotheses that will guide more mechanistic studies towards understanding epigenetic events that directly and indirectly influence the course of pulmonary lung infections.